Oil-switch.



E. M. HEWLETT.

OIL SWITCH.

APPLICATION FILED T13R23, 1906.

Patented Nov. 26, 1912.

2 SHEETS-SHEET 1.

mentor, Edward MHewle dc. by w f Witnesses- B. M. HEWLETT.

OIL SWITCH. APPLICATION IILED FEBfZS, 1906.

Patented Nov. 26, 1912.

2 SHEETS-SHEET 2.

Ill Ill/ mvelytorz Edward M. Hewlett a: xx

EDWARD UNITED STATES PATENT OFFICE.

HEW LETT, OF SCHENE CT AIDY, NEW YORK, ,A SSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.-

oIL-swrrcrr.

Specification of Letters Patent.

Patented Nov. 26, 1912.

Application filed February 23, 1906. Serial No. 302,438. r

T 0 all whom it' concern:

Be it known that-I, EDWARD M. HEwLn'rr,

a citizen of the United States, residing at Schenectady, in the countyof Schenectady,

State of New, York, have invented certain new and useful Improvements in011;

ties are encountered by reason of new-problems which requireextraordinary provisions to insure safety of operation and preventdanger to apparatus and operators. lhe present switch will safely handlepotentials of 100,000 volts and upward, chieflyby reason of the novelconstruction which prevents breaking down of insulation and insures'safe extinguishment of the powerful arc. In order to prevent destructionof the apparatus, the distancebetween those parts of the controllingdevices which may be atdif-' ferent potentials must be increased as thepotential of the circuit increases, and this distance becomes so greatwith extremely high voltages that the space factor becomes extremelyimportant and renders the buildings unduly expensive.

The object of this invention therefore is to provide an improvedapparatus of as small compass as is consistent with safety of operation,which shall be capable of con trolling with ease and safety eithersingle or pclyphase circuits carrying currents of high potentlals of theorder hereinbefore.

referred to and of'large amperage; to reduce the floor space required ascompared with devices heretofore used to control such cn-cuits; tosimplify and strengthen the structure and increase the reliability andefliciency of operation; to make the insulation safe to avoid thepossibility of destruc tive arcs being formed from one part of theapparatus to another ,through the air; to extinguish quickly and surelythe are formed ,when the contacts separate to 0 en the circuit; toprovide means, for quic ly and positively opening or closing thecircuit;

As the potentials ofand in general to render perfect the operation ofcontrolling apparatus for circuits of high potential.

My invention consists, in general, of a vessel containing oil or otherinsulating liquid, relatively movable contacts int-he ends of the vesselthoroughly insulated therefrom and connected to the leads of-thecircuit, and means for bringing the contacts into engagement or forseparating them to close or to open the circuit. The contacts arepreferably below the surface of the oil in the vessel and soarrangedthat only one is movable and shifts toward the bottom'of the vessel whenthe circuit is broken. The movable contact may be actuated in any waydesired, but it is considered preferable to actuate the contact by someother force v than the strength of the operator and to do it with greatrapidity to prevent any considerable are products being formed; and mylnvention furthermore consists in. providing a device, mounted at oneend of the preferably compressed air.

viding means for storing a sufficient supply of compressed air tooperate the device and open the circuit in case the device for supplyingcompressed air fails to operate for any reason.

vessel and insulated therefrom, for actuating V the movable contact bysome power medium,

My invention furthermore consists in pro- My invention also consists ofmeans for drawing the are in a strong small chamber filled with oilhaving small vents by reason of which the tremendous energy of the arcdevelops great pressure, and thus squeezes or contracts the arc streamthus increasing its ohmic resistance.

It consists also of additional means for increasing the arc resistanceby causing themovable terminal to retreat through. a small hole in aninsulating diaphragm and then traverse a long path in the oil.

It comprises also other details of construction and of combinations ofelements hereinafter described and pointed out in the claims.

The invention will be best understood by reference to the accompanyingdrawings, in

whichv Figure 1 shows the switch in elevation;

Fig. 2 is a plan view; Fig. 3 is a side eleva- L tion, showing themanner of supporting the switch; Fig. 4 is a sectional view of a cell ofthe switch; Fig. 5 is an enlarged sectional View of the fixed contactand surrounding parts; Fig. 6 is an enlarged sectional view of the upperend of the motor for operating the movable contact; and Fig. 7 is a viewin elevation of the storage reservoir and distributing valve.

Theparticular switch shown in the drawings is for the purpose ofcontrolling a three-phase circuit, although it will be apparent toengineers that the device may be modified to control a circuit of anynumber of phases. In the arrangement shown three cells are provided eachcontrolling one of the phases of the circuit and all simultaneouslyopened or closed. Each cell consists of acasing 1 mounted in anyconvenient way and provided with a good ground. A masonry or othersuitable wall 2 carries a series of brackets 3, which support twochannel iron beams 4. The casings 1 of the cells are secured to thebeams 4 by means of clamps 5, consisting of iron bands encircling thecasing and holding the casings firmly in position by means of nutsthreaded on the ends of the bands and engaging the beams;

At the upper end of each casing a tubular contact rod 6 is mounted, towhich a conductor 7 leading to the line is connected. The tubularcontact rod is secured to a head 8 at one end, and carries a nut 9 atthe other end. It is suppofted on the end of the easing and insulatedtherefrom by an insulator composed of a series of annular sections 10,and porcelain caps 11 and 12, the Whole being held together by thetubular contact rod 6. The sections 10 are formed of indurated fiber, orany suitable insulating material, and disks 13 of insulating materialare placed between the sections, projecting beyond the outer surface ofthe sections in order to increase the creepage surface of the insulator.The lower porcelain cap 11 is cone shaped, and may have ribs orprojections on the surface. This cap projects downward into the casing,and the lower end thereof may be beneath the surface of oil in thecasing. The lower end of the cap 11 is engaged by an insulating disk 1which is held in position between the cap 11 'and the head 8 of thetubular contact rod.

The upper end of the cap 11 is in engagement with the lower surface of acover 15,

which closes the top of the casing. The bottom one of the sections 10 isin contact with the upper surface of the cover 15, and

the walls of a short tube the ends of which are closed by the caps 11and 12. A small opening 16 is provided in the tubular contact rod 6forming a passage between the interior of the insulator and the interiorof the rod. The interior of the insulator is filled with oil or otherinsulating liquid by pouring the oil into the upper end of the tubularcontact rod 6. The oil rises quietly in the insulator, and no airbubbles are formed. Partitions 17, preferably but not necessarily ofinsulating material, are arranged in the interior of and concentric withthe walls of the insulator, thereby dividing the oil into a series ofconcentric layers. It has been found that this arrangement materiallyincreases the dielectric strength of the body of oil.

The head 8 carries a ring contact 18, folmed of a series of segmentsheld in posi tion by springs which tend to move said segments toward thecenter of the ring. The contact 18 is held in place by a sleeve 19screwed into the head 8. The head 8 is provided with" an axial passage20 and a transverse passage 21, of small area, forming'a restrictedVent. A plug may be placed in the end of-the passage 21 and a smallopening transverse to the passage provided, in order to diminish thevelocity of the gases passing through the passage 21. p A pressureaccumulating and restraining chamber 22 is secured to the head 8 bybolts or in any other suitable way; This chamber is preferably formed ofpressed steel and is of great strength. The lower edges of the chamberare turned inward and support a closure 23 which carries a sleeve 94,preferably of insulating material, but not necessarily so, as the sleevemay be made of metal, if insulated from the head 8. The opening throughthe sleeve 24 is preferably cone shaped, and larger at the bottom thanat the top. The chamber 22 is lined with insulation 25 while aninsulating sleeve 26 loosely surrounds the chamber and is held againstthe insulating disk 14: by a disk 27, which in supported by the chamber22. Vents 28 are provided in the disk 1-1 to permit air or gas to escapefrom the chamber 22 by way of the passages 20 and 21 without disturbingthe body of oil surrounding the chamber Oil may form a thin layer ofinsulation be tween the chamber '22 and the sleeve 26. which is notdisturbed by movements of the oil in the casing 1. i

The lower end of the casing 1 is closed by an insulator constructed insubstantially the same manner as the insulator mounted on top of thecasing. The lower insulator is held together by a tube 29 carrying ahead 30 at the upper end and a nut 31 threaded on the tube at the lowerend. The head 30 and the nut 31 engage porcelain endpieces 32 and 83,and thereby hold the is less than the inner-diameter of the tube.

As a result of this construction, there is formed an annular chamber 86between the outer wall of the cylinder and the innerwall of the tube.This chamber 36 communicates with the interior of the cylinder at theupper end thereof by means of ports 37, which are located a shortdistance from the head 30. A piston 38 works in the cylinder 35 andcarries a tubular piston-rod 39 passing out through a stufiing-box 40 onthe upper end of the insulator. The stufling-box is formed with severalglands 41 to insure durability. The tubular piston-rod 39 ear ries atthe upper end thereof'a contact-rod 42 which passes through the sleeve24 in the chamber'22 and comes into engagementwith the fixed cont-act18. The cylinder 35 is preferably made of brass or other good conductingmetal, and is in electrical connection by means of the connector 43 andthe tube 29 with a lead 44 connected to the generator. As a result ofthis arrangementthe cylinder 35 is always at the potential of thegenerator lead and current flows through the lead 44 to thecylinder 35,thence to the piston 38, through the tubular piston-rod 39 to the fixedcontact 18 and to the line. The cylinder 35 and piston 38 form a motorfor actuating the movable contact which is operated by means ofcompressed air supplied through pipes 45 and 46. interior of thecylinder 35, while the pipe 46 communicates with the annular chamber 36between the cylinder and the tube. The admission of compressed air tothe cylinder 35 through these pipes is controlled by mechanismhereinafter described.

The casing of the switch is provided with an insulating lining 47extending from the bottom of the switch to within a short distance ofthe top thereof. The upper end of the casing iis enlarged and isprovided with an insulating lining formed of two concen tric walls 48and 49 of insulating material, these walls being connected .at thebottom. The walls of insulating material extendto the top of the casing,and the annular space between the insulating walls is filled with oil orother insulating liquid. When the switch is in use oil is put into thecasing so that the chamber 22 is submerged, but the oil does not reachto the top of the casing 1. The insulating walls 48 and 49 extend to thecover, which closes the upper end of the casing. These insulating wallswith the layer of oil between them form a lining operated.

The pipe 45 communicates with the,

for the upper end of the switch, which is not affected by any movementof the body of oil in the switch casing. It may occur in the operationof the switch that the arc gases formed on opening the circuit willescape from the chamber 22 and bubble up through the body of oil,thereby materially decreasing the dielectric strength of the body of oiland set-ting up a path of comparatively low resistance between thechamber 2:2 and the upper end of the casing 1. The insulating walls andthe layers of undisturbed oil between them, however, provide a lining ofsufficient dielectric strength to prevent the passage of a spark fromthe chamber to the casing, even though all the oil between the chamberand the insulating lining were removed.

The lining 47 is concentric with the casing of the switch and with thelinings 48 and 49 divides the body of oil into sections. The lining 47does not extend to the surface of the oil, and is for the purpose ofpreventing displacement of the oil when the switch is When the circuitis opened the are produced tends to blow the oil out of the casing anset up disturbances which decrease the insulating power of the body ofoil. As a resultof the use of the lining 47 any, disturbance in the oilcaused by the arcwill be confined to the immediate neighborhood of thecontacts,.and a layer of oil between the lining 47 and the casing 1remains undisturbed.

In order to allow for the escape of the vapors and gases caused by thearc, vents 50 are provided in the upper cover 15 of the casing. Thesevents are not large, and

permit the free escape of the vapors, al-

though tending to prevent the oil splashing out of the switch casing. Aring 51 mounted on the cover prevents loss of oil.

In order to insurethat the oil is maintained at the proper level, agage-glass 52 is connected to the interior of the casing at a point welldown where the oil is not disturbed or agitated so that the attendantcan A see at all times the level of the oil.

In order that the stufling-box may be repacked or tightened up in caseit should become necessary, hand-holes G0 are provided in the casing,the each hand-hole being closed by a plate. The holes are large enoughto permit the attendant to reach the stuffing-box and make any necessaryrepairs thereto. The sections of the casing are detachably securedtogether, and may be separated to facilitate repairs which cannot bemade through the hand-holes.

The switches are operated bymeans of compressed air, which may befurnished from any convenient source, such as a pump or compressor,operated either by hand or by power. '.It is evident that any fluidunder pressure could be used and also that the switches might beoperated by means of rods connected to the movable contacts, the rodsbeing moved in any, convenient manner. In a large station, where severalswitches are in use, an air compressor may beinstalled, driven by aninduction motor is composed of three cells, the reservoir 53 of eachswitch supplies air to all three cells.

As it is desirable that the air used in operating the switches be verydry, some sort of dryer is preferably placed either between thecompressor and the supply reservoir or between the supply reservoir andthe storage reservoirs of each of the switches. The dryers may .be anyof the well-known devices used for removing moisture from air. Acheck-valve 54 is provided between the supply reservoir and each storagereservoir 58 for the purpose of admitting air to the storage reservoirs,but preventing the passage of air from the storage reservoirs to thesupply reservoir. The purpose of this arrangement is to insure a supplyof air in the storage reservoir sufiicient to open the switch eventhough the air compressor or the supply reservoir should fail.

The dry air from the storage reservoir 53 is led to the switches throughthe pipes 45 and 46. These pipes, substantially equal in length," arecomposed of insulating material, and are of such length that there willbe no leakage of current from the generator lead along the pipes to thestorage reservoir. A portion of the pipes is preferably made of glass inorder that any leakage of oil through the stufling-box, into-thecylinder and into the pipes, may be readily detected and also in orderthat moisture in the air for operating the switch may be detected by theattendant.

Air from the storage reservoir 53 is dis a distributing valve of anydesired form,-

mounted in a valve chest 55. It is'evident that many forms ofdistributing valve could be used to deliver air to the pipes 45 and 46at the proper times. and the slide valve 56 shown in the drawings ismerely an illustration of one of the numerous forms which may be used.This valve is a sliding D- valve. The valve is mounted in the chesthaving ports 57, 58 and 59. The port 57 is an exhaust-port and opens tothe air. The port 58 communicates with the pipes 46, which lead into theannular space between the tube' anti3 cylinder. The other port 59communica s with the pipes 45 which lead to'the interior of thecylinders of the switches. The valveis so proportioned that when innormal position both port 58 and port 59 are in communication withexhaust port 57, thereby permittin exhaust to atmosphere from both ends0 the operating cylinder. Theldistributing valve 56 maybe operated inany desired manner, either by the hand of the operator in charge of theswitches or in any other desirable way, as by solenoids. Springs areprovided, as indicated, which tend to return the distributing valve toits normal position, whenever the operating means is released.

The operation of the circuit controlling device is as follows: Assumingthe switch to be closed, the movable contacts are in en- I gagement withthe fixed contacts. The distributing valve 56 is moved so as to uncoverthe port 58. Compressed air flows from the storage reservoir through thepipe 46 to the annular space 36 between the tube and the cylinder ofeach switch, and, acting upon the upper-surface of the piston, forces itdownward,'thereby separating the contacts and opening the circuit. Asthe contacts separate an arc is formed in the chamber 22, but the forceof the explosioncaused by this are is confined to=the chamber 22, and asthe arc gases rush out through the sleeve 24 in the bottom of thechamber, the gases are cooled by the surrounding oil. The breaking ofthe arc is aided by the rapidity with which the moving contact leavesthe stationary contact. The movable contact,

after withdrawing from the small cylinder ward movement in oil.- Inorder to close the switch, the distributing valve is moved to the otherposition. The port 59 is uncovered. admitting compressed air to theinterior of the cylinders. When the valve 56 returns to normal position,after having been moved to open the switch, communication is establ shedbetween the ort 58 and port 57. thereby permitting the air to escapefrom the upper end of the cylinder through the annular space 36 betweenthe tube and the cvlinderfthe pipe 46 and the port 57 to the outer air.The pressure of the air beneath the-piston forces the piston upward andbrings the contacts into engagement, thereby closing the circuit.

The distributing valve 55 is placed below the level of the cylinder 35,so that the pipes 45 and 46 are given enough inclination to cause anymoisture or oil which may accumulate-in the pipes to drain toward thevalve. 55.

Many changes and modifications may be made in the structure abovedescribed by those skilled in the art Without departing from myinvention, and Itherefore do not regard my invention as lim ted to theexact structure shown, but conslder all changes in structure andarrangement that are within the scope of the appended claims, to bewithin the scope of my invention.

Vi hat I claim as new and desire to secure by Letters Patent of theUnited States,

1. In an electric switch, the combination of a metallic support,relatively movable cooperating contacts mounted on and insulated fromsaid support, fluid pressure 010- j mounted on one of said insulators,fluid pressure operating mechanism mounted on the other of saidinsulators, a movable contact mounted on said mechanism to be carriedinto and out of engagement with said stationary contact, and insulatingmeans for supplying fluid under pressure to said operating mechanism.

3. In an electric switch, the combination of a metallic support, aninsulator secured to said support, fluid pressure operating mechanismmounted on sa1d 1nsulator,and

connected to one lead of the circuit to be controlled, a movable contactmounted on said operating mechanism and moved thereby into and out ofcircuit closing position, insulating means for supplying'fluid underpressure to said operating mechanism, and a stationary contact insulatedfrom said support and mounted thereon in a position to be engaged bysaid movable contact.

at. In. an electric switch, the combination of a metallic vesselcontaining oil, a stationary contact mounted on and insulated from onewallot' said vessel in a position to project into the oil in saidvessel, a fluid pressure operating mechanism mounted on and insulatedfrom another wall of said vessel and projecting into the oil in saidvessel, a movable contact carried by said operating mechanism into andout of engagement with said stationary contact, and insulating means forsupplying fluid under pressure to said operating mechanism.

5. In an electric switch, the combination of a metallic vesselcontaining oil, a stationary contact mounted on said vessel to projectinto the oil in said vessel, a cylindrical insulatoi; mounted in anotherwall of said vessel, a 'm'etal'lic cylmdercexteiidmg through saidinsulator longitudinally thereof and connected to one lead of thecircuit to be controlled, a metallic piston in said cylinder, .ametallic contact mounted on and carried by said piston, and insulatingmeans for supplying fluid under pressure to said cylinder to cause saidpiston to carry said movable contact into and out of engagement with thestationary contact.

6. In an electric switch, the combination I with a metallic vesselcontaining insulating fluid, of a stationary contact insulated from andmounted on one end of said vessel, amovable contact mounted to cooperatewith said fixed contact, fluid pressure operating mechanism insulatedfrom and mounted on the other end of said vessel and comprising a metalguide for said movable contact, said guide-being connected to form partof the circuit to be controlled, and insulating means for supplyingfluid under pressure to said operating mechanism.

7 In an electric switch, the combination fluid, of a stationary contactat one end of said vessel, a movable contact insulated from said vesseland mounted to cooperate with said fixed contact, fluid pressureoperating mechanism forsaid movable contact mounted on and insulatedfrom the opposite end of said vessel, and insulating means ,for supwitha metallic vessel containing insulating plying fluid under pressure tosald operatmg mechanlsm.

8. In an electric switch, the combination with a vessel containinginsulating fluid, of

j a stationary contact arranged to project into said vessel, aninsulator mounted on said vessel at one end thereof, a cylinder carriedby said insulator, a piston in said cylinder, a movable contact actuatedby said piston to cooperate with said fixed contact and connected to onelead of the circuit to be controlled, and insulating means for sup lyingfluid under pressure to said cylinder or actuating said piston.

9. In an electric switch, the combination with a metallic vesselcontaining insulating fluid, of a stationary contact mounted on andinsulated from one wall of said vessel, an insulator mounted on anotherWall of said vessel, a metal cylinder mounted in said insulator andconnected to one lead of the circuit to be controlled, a piston in saidcylinder, a movable contact mounted on said piston and carried therebyinto, and out of engagement with the stationary contact, and insulatingmeans for supplying fluid und er pressure to said cylinder to actuatesaid piston.

10. Inan electric switch, the combination with. a vessel containinginsulating fluid, of cooperating relatively movable contacts, aninsulator mounted on one wall of said vessel, fluid pressure operatingmechanism comprising a metallic cylinder and a} piston mounted in saidinsulator and connected to one of said contacts, a source of supply offluid under pressure, and insulating connections between said source andsaid fluid pressure operating mechanism.

11. In an electric switch, the combination with a vessel containinginsulating fluid, of a stationary contact mounted to project into saidfluid, a cylinder mounted on and insulated from said casing andconnected to one lead of the circuit to be controlled, a piston in saidcylinder having a piston rod formed as a contact to cooperate with saidfixed contact, insulated pipes connected to the opposite ends of saidcylinder, and means for introducing at will fluid under pressure to saidpipes.

12. In an electric switch operated by fluid under pressure andcomprising a vessel containing insulating liquid, the combination withan insulated fluid pressure operating mechanism connected to one lead ofthe circuit to be controlled and mounted on said vessel to projectthrough thewall thereof below the surface of said liquid, of adistributing valve for fluid provided with an exhaust port and placedbelow said mechanism, and insulating pipes leading upward from saidvalve to said operating mechanism.

13. In an electric switch, the combination with a metallic casingconnected to the ground, of cooperating switch contacts carried thereby,and insulators for supporting said contacts composed of annular sectionsforming the walls of a chamber for insulating liquid, caps closing theends of said chamber, and means for holding said caps in position.

14. An electric switch comprising a vertical switch cell, hollowinsulators containing oil at each end of the cell, porcelain caps forthe insulators carrying the leads and the contacts, a pressure chamberin which the arc is drawn mounted on the upper insulator. and a movablecontactmounted in the lower insulator, whereby anarc of high potentialmay be drawn by a long movement of the movable contact.

15.- In an electric switch,, the combination of a vessel containing oiland a cover for said vessel, of a porcelain cap engaging the inner sideof said cover, a chamber filled with oil having walls formed of annularsections engaging the outer side of the cover, a cap for closing theouter end of said chamber, partitions concentric with the walls of saidchamber, and means for holding said porcelain cap and said annularsections'in liquid, of an insulating lining for said cas-' ing, andaplurality of walls mounted concentric with the walls of said casing toplace the spaces between said walls in communication and to divide theliquid into layers. -17. In an electric switch, the combination with avessel containing an insulating liquid, of coiiperating' relativelymovable contacts therein, and a plurality of 'walls withintercommunicating spaces between them mounted concentric with the wallsof the vessel to divide the liquid into layers.

18. In an electric switch, the combination with a-vessel containing aninsulating liquid, of cotiperating relatively movable contacts therein,and a plurality of partitions mounted concentric with the walls of thevessel with spaces between the partitionsthe liquid is diwith acylindrical vessel containing oil, and

cotiperating relatively movable contacts beneath said oil, of acylindrical oil restraining wall mounted concentric with the walls ofsaid vessel to surround said contacts and to permit the oil to flow overone end of'said oil restraining wall and thereby establish communicationbetween the oil on both sides of said wall. 1

20. In an electric switch, the combination with a cylindrical vesselcontaining oil and relatively movable cotiperating contacts therein, ofan annular vessel having a central opening therein and set within saidcylindrical vessel to surround said contacts, said annular vessel beingfilled with oil to form an annular insulating wall around said contacts.

21. In an electric switch, the combination with a vertical cylindricalvessel containing an insulating liquid, of coiiperating relativelymovable contacts, and a plurality of vertical concentric walls immersedin the liquid around the contacts with the spaces between said walls incommunication.

' In witness'whereof I have hereunto set my hand this 21st day ofFebruary, 1906.

' EDWARD M. HEWLETT.

Witnesses: Y

BENJAMIN B. HULL, HELEN ORFORD.

